(1) Work groups may be determined for workers carrying out work for 2 or more persons conducting businesses or undertakings at one or more workplaces.
(2) The particulars of the work groups are to be determined by negotiation and agreement, in accordance with section 56, between each of the persons conducting the businesses or undertakings and the workers.
(3) The parties to an agreement concerning the determination of a work group or groups may, at any time, negotiate a variation of the agreement.
(4) The determination of one or more work groups under this Subdivision does not--(a) prevent the determination under this Subdivision or Subdivision 2 of any other work group of the workers concerned, or(b) affect any work groups of those workers that have already been determined under this Subdivision or Subdivision 2.